Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ~C exhibit photoluminescence （PL） ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitio...Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ~C exhibit photoluminescence （PL） ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitions of lone pair （LP） states of intra-tri-s-triazine and inter-tri-s-triazine nitrogens. The proposed PL mechanism is further confirmed by diffusion reflectance spectroscopy, as well as time-resolved and temperature-dependent PL. This intense fluorescence is stable at different pH and resistant to UV exposure, suggesting that this inexpensive broadband luminescent material could be significant for white- light-emitting （WLE） applications. Thus, quasi-WLE films and membranes with designed patterns are fabricated by embedding the carbon nitrides into polymethyl methacrylate. Moreover, even broader PL （400 to 740 nm） is acquired in com- posite films composed of carbon nitrides, further suggesting that the carbon nitrides are robust candidates for WLE.展开更多
Multicolor fluorescence of mixed halide perovskites enormously enables their applications in photonics and optoelectronics.However,it remains an arduous task to obtain multicolor emissions from perovskites containing ...Multicolor fluorescence of mixed halide perovskites enormously enables their applications in photonics and optoelectronics.However,it remains an arduous task to obtain multicolor emissions from perovskites containing single halogen to avoid phase segregation.Herein,a fluorescent composite containing Eu-based metal-organic frameworks(MOFs),OD Cs PbBre,and 3D CsPbBrs is synthesized.Under excitations at 365 nm and 254nm,the pristine composite emits blue(B)and red(R)fluorescence,which are ascribed to radiative defects within CsPbBr and 5Do→7F,transitions of Eu^(3+),respectively.Interestingly,after light soaking in the ambient environment,the blue fluorescence gradually converts into green(G)emission due to the defect repairing and 0D-3D phase conversion.This permanent and unique photochromic effect enables anticounterfeiting and microsteganography with increased security through a micropatterning technique.Moreover,the RGB luminescence is highly stable after encapsulation by a transparent polymer layer.Thus,trichromatic light-emitting modules are fabricated by using the fluorescent composites as color-converting layers,which almost fully cover the standard color gamut.Therefore,this work innovates a strategy for construction of tunable multicolor luminescence by manipulating the radiative defects and structural dimensionality.展开更多
文摘Carbon nitrides synthesized by thermal polycondensation of melamine at 700 ~C exhibit photoluminescence （PL） ranging from 400 to 650 nm. This broad PL is attributed to band to band transitions and bandtail transitions of lone pair （LP） states of intra-tri-s-triazine and inter-tri-s-triazine nitrogens. The proposed PL mechanism is further confirmed by diffusion reflectance spectroscopy, as well as time-resolved and temperature-dependent PL. This intense fluorescence is stable at different pH and resistant to UV exposure, suggesting that this inexpensive broadband luminescent material could be significant for white- light-emitting （WLE） applications. Thus, quasi-WLE films and membranes with designed patterns are fabricated by embedding the carbon nitrides into polymethyl methacrylate. Moreover, even broader PL （400 to 740 nm） is acquired in com- posite films composed of carbon nitrides, further suggesting that the carbon nitrides are robust candidates for WLE.
基金supported by the Natural Science Foundation of Shandong Province(ZR2021YQ32)the Taishan Scholars Program of Shandong Province(tsqn201909117)+1 种基金support was given by the National Natural Science Foundation of China(6190i222,21802074,and 11604155)Natural Science Foundation of Jiangsu Province(BK20190697).
文摘Multicolor fluorescence of mixed halide perovskites enormously enables their applications in photonics and optoelectronics.However,it remains an arduous task to obtain multicolor emissions from perovskites containing single halogen to avoid phase segregation.Herein,a fluorescent composite containing Eu-based metal-organic frameworks(MOFs),OD Cs PbBre,and 3D CsPbBrs is synthesized.Under excitations at 365 nm and 254nm,the pristine composite emits blue(B)and red(R)fluorescence,which are ascribed to radiative defects within CsPbBr and 5Do→7F,transitions of Eu^(3+),respectively.Interestingly,after light soaking in the ambient environment,the blue fluorescence gradually converts into green(G)emission due to the defect repairing and 0D-3D phase conversion.This permanent and unique photochromic effect enables anticounterfeiting and microsteganography with increased security through a micropatterning technique.Moreover,the RGB luminescence is highly stable after encapsulation by a transparent polymer layer.Thus,trichromatic light-emitting modules are fabricated by using the fluorescent composites as color-converting layers,which almost fully cover the standard color gamut.Therefore,this work innovates a strategy for construction of tunable multicolor luminescence by manipulating the radiative defects and structural dimensionality.
